DIFFUSION HYDRODYNAMIC MODEL OF SHALLOW ESTUARY

Many of the hydrodynamic models used for estuary tidal flows and storm surges are based on a set of coupled two-dimensional hydrodynamic equations, which are obtained from the full three-dimensional flow equations by averaging the vertical coordinates. Various numerical techniques, such as finite difference, finite element, and the method of characteristics, have been used to solve these equations. The diffusion hydrodynamic model (DHM) has been developed to simulate two-dimensional surface-water and channelized flows. In a prior study, the DHM was applied to a deep-water estuary with computational results, comparable to those obtained using the St. Venant equations and the method of characteristics. In this paper, the DHM is applied to a shallow estuary located in southern California. The main objective is to determine local flow velocities and circulation patterns in the shallow estuary caused by the incoming and the outgoing tide. Verification of the DHM is provided by comparison of tidal gage measurements and computed flow depths.